Yes, they do differ. These aren't the stock columns, but Silvermine matches the stock mount points, so it works for comparison.
I plan on going power steering anyway, so if the wheel mount is the only difference, I could just pick up a 280Z column instead. I think I might be able to just make the 4 matching holes in the 280z pedal box, though.
I've never actually removed my dash or steering column from the car. The two pictures below are of the two dash frames. First is a 280Z, and the second is a RHD 240Z. They both only seem to have two holes in the steering column area, presumably for the top set of mount holes in the case of the 240Z, since its bracket is lower.